Novel process for soap purifying



1949- F. LILACHAMPT NOVEL PROCESS FOR SOAP PURIFYING Filed May 24, 1946 MM f V m WflW J iv ..v TH w B G iv... m

Patented Oct. 18, 1949 2,485,204 NOVEL'PROCESS FOR SOAP PURIFYING Felix Lucien Lachampt, Franconville, France, assignor to Union Francaise Commerciale et Industrielle, a society of Morocco Application May 24, 1946, Serial No. 672,082 In France July 31, 1943 Section 1, Public Law 690, August 8, 1946 Patent expires July 31, 1963 8 Claims (01. 260-418) The importance of salting out in soap manufacture according to the so-called Marseilles process is well known. Such salting out makes it possible to reclaim glycerol which was freed during saponification and has remained within the soap. The salting out operation makes it possible also to eliminate the oxidized fatty acid soaps, which constitute rancidizing factors. Said saltin out operation is based on the fact that, by adding to a dilute solution of soap an electrolyte in sufiicient quantity, the homogeneousness of the solution is destroyed and the solution first ,becomes cloudy and then segregates somewhat slowly into two layers, one of which, the upper layer, comprises practically the totality of the soap, and is poor in electrolyte, while the lower layer contains but little soap and a large proportion of the electrolyte, together with the glycerol which thus is segregated and may be reclaimed. It is known that there is thus produced a true equilibrium between the liquid soap phase and the salty solution called: lower lye; the electro lyte concentration of the soapy phase is a function of the electrolyte concentration of the lower lye and this lower lye has a certain minimum electrolyte concentration below which said solution still continues to dissolve some soap. It is this critical concentration which should be reached in order to carry out the desired complete separation between the soap and glycerol. soap thus salted out still contains salts in an amount, which is troublesome with regard to subsequent treatment and the quality of the finished soap product. The major proportion of such salts may be eliminated by the so-called liquidation step. This operation consists of adding water to the soap in such quantity that a certain amount thereof will become dissolved in the lower lye. A new balance or state of equilibrium is thus obtained; on one hand, soap in the state of a concentrated liquid phase and, on the other hand, a salty solution of the soap called nigre; in this balance, the upper portion is rich in soap and has become poorer in salts, which have migrated to the lower portion or nigre, which is poorer in soap. But, the abov segregation only proceeds slowly.

This invention has for its object to substitute for the salting out process a rapid separation process carried out by starting, not from a dilute solution, but rather from a soap obtained in the liquid phase thereof in which said concentration is the highest. This phase being sometimes termed the neat phase. 1 Y v .The novel process accordin to the invention The thus makes it possible to utilize an alkaline soap directly without it being necessary to carry out the usual liquidation step.

The purifying process, which is an object of the invention, comprises a series of washing operations preferably carried out in counter current stages and at a temperature approximating C. on the soap in the neat phase by means of electrolytic solutions, the concentration of which preferably is higher than the critical concentration. Such novel methodical washing process is based on the following observation. When the neat soap is put in the presence of a salty solu-' tion having a concentration greater than the critical one, not only is said soap not dissolved in said solution, but promptly separates therefrom; such solution may then exhaust the soap phase by retaining the glycerol and the oxidized fatty acid soaps in the same way as for instance water may exhaust an alcohol-benzine solution in the presence of alcohol.

It therefore will easily be understood that it is possible very advantageously to eliminate the glycerol and the brine soluble impurities by methodically washing the soap by means of salty solutions having a concentration slightly in excess of the critical concentration; the operation is carried out almost instantaneously without any precipitation or dissolution of the soap; it may be carried out continuously, which will be of particular advantage in connection with the continuous processes of soap manufacture.

There is thus obtained a soap, which is purified but has a salt-content which'is too high, as a result of the exchange which has taken place between the soap and the salty solutions.

It goes without saying that the process forming the object of this invention could, strictly speaking, be considered as implying washing the soap by means of electrolytic solutions having a concentration less than or equal to the critical concentration; the loss in dissolved soap would then simply be the more great as the concentration would more greatly differ from said critical value.

Instead of thereafter effecting a continuous liquidation operation by adding water in suitable amounts to cause a segregation into neat-nigre phases, as ordinarily practiced in this liquidation step, it is preferable to carry out one last washing operation by means of a sodium hydrate lye having a concentration preferably in excess of the critical one. There is thus produced a soap in which a large proportion of excess salt has been exchanged against free sodium hydrate,

The lower alkaline lye, which has exhausted or drained the salt from the soap solution, may be used for preparing the saponifying lye.

The strongly alkaline soap thus obtained is finally processed by a fast-actin saponifying fat such as cocoanut, and the like, by a fatty acid or a buffer mixture or a silica gel or any other product or mixture capable of neutralizing the free sodium hydrate while allowing a final soap product of suitable grade to be obtained. Such addition of fatty acid may be completed by a further addition of another fatty or non fatty acid or of any other product enabling a suitable soap to be obtained, so that, at the discharge end of the machine, the soap has a concentration making any further drying unnecessary, and may at once be milled, molded and formed or subjected to any other treatment which may be required for the production of a commercial soap.

The advantages offered by the process according to the invention are numerous and important. The following may be more specifically mentioned:

(1) High speed of operation, which may be carried out without a break or any discontinuity.

(2) Uniformity in operation, the equality of the soap being but slightly affected by small variations in the concentration of the alkaline lye and the final free sodium hydrate content of the soap being only dependent on the con centration of the alkaline washing lye, said ulti-' mate washing step having a regulating or adjusting function.

(3) Saving in steam consumption since the whole process is carried out in a sealed enclosure and the heat expended being utilized to bring to a temperature of 100 C. the salt solution, which is discharged from the machine at the same temperature, thus making it quite easy subsequently to obtain the concentration required for reclaiming the glycerol. Lastly, the speed of the operation averts any losses of heat which are considerable in discontinuous processes wherein the soap remains in the tank for several days.

(4) Dimensions of the plant are reduced to a minimum because of the continuity of the process.

(5) A considerable output rate may be achieved by carrying out rapid settling operations.

(6) An important saving in man power may be brought about due to the automaticity of the process.

By way of indication and by no means of limitation and in order to make the organisation of the invention more easily understandable, there is described hereafter an exemplary embodiment of the improved purifying method.

In this specific embodiment, the soap, such as tallow soap for example, is discharged at 100 C. from the saponifying apparatus in the state of neat soap having 63% of soap. The product is washed with a brine having a concentration slightly above the critical concentration such as, for instance, 12% sea-water salt for a volume of lye equal to the volume of soap.

The critical concentration, as defined above, is not only variable according to the state of the soap and the glycerol content thereof, but also depends on the respective proportions of soap and lye. The washing operation is carried out in three counter current stages in an apparatus which is schematically illustrated in the single figure of the annexed drawing. All

such washing Operations are effected at a constant temperature such as 99 0., for example.

The neat soap containing glycerol enters the machine at A. The glycerol is eliminated therefrom at B after the feed has travelled along a path indicated in the drawing by arrows drawn in full lines. The brine is fed into the apparabus at C and is discharged therefrom at D after having become loaded with glycerol during its travel along the path indicated by arrows in dashes.

The soap at B, washed but containing salt, is then subjected to an ultimate wash by means of a 10% NaOI-I solution fed at F. The alkaline soap is conducted to H while the alkaline lye is discharged at G after having travelled along the path indicated in the drawing by arrows in dotted lines, into a storage tank, not shown, where it will ultimately serve to prepare the saponifying lye. The alkaline soap collected at H is mixed with a fatty acid, which neutralises the excess sodium hydrate. Said fatty acid is contained in a tank I. The finished soap product in neutral and concentrated condition is discharged at J, ready to be converted into commercial soap.

As shown in the drawing there are provided four mixing and separating stages E0, E1, E2, and E3. Each of these stages comprises a tank such as r0, r1, 12, and r3. Into tanks r1, T2, and 113 the brine solution is introduced while into the tank re the sodium hydroxide is introduced. There is also associated with each stage the mixers such as 1m, m1, m2, and me which insure proper contacts between the washing lye and the soap. Finally there is associated with each stage a static separator such as so, s1, s2, and s3 wherein there occurs continuous settling and separation of the washing lyes and the soap. Volumetric pumps, not shown in the drawing, provide for the proper proportioning of the reagents and the circulation of the liquids.

It will be understood that the number of washing stages could be varied and each of said stages could be organized in a different manner from that shown without exceeding the scope of the invention, provided continuous counter current methodical washing of the soap in a concentrated liquid phase is carried out.

What I claim is:

1. In the manufacture of soap a continuous process for the purification of a glycerinated soap obtained in the more concentrated liquid phase known as neat soap comprising washing the soap by a continuous circulation with a solution of sodium chloride and the concentration of said solution being close to the concentration below which the soap may be dissolved.

2. In the manufacture of soap a continuous process for the purification of a glycerinated soap obtained in the more concentrated liquid phase known as neat soap comprising washing the soap by a continuous circulation with a solution of sodium chloride and the concentration of said solution being closely above the concentration below which the soap may be dissolved.

3. In the manufacture of soap a continuous process for the purification of a glycerinated soap obtained in the more concentrated liquid phase known as neat soap comprising washing the soap by a continuous circulation with a solution of sodium chloride and. the concentration of said solution being closely below the concentration below which the soap may be dissolved.

4. A process for the purification of soap in accordance with claim 1 in which the first washing with the aid of sodium chloride is followed by a second continuous washing with a solution of sodium hydroxide, said last named washing solution having a-concentration closely above the concentration below which-the soap may be dissolved.

5. In the manufacture of soap a process for the continuous purification of aglycerinated soap obtained in its most concentrated liquid phase known as neat soap phase comprising washing the soap by a continuous countercurrent circulation in a plurality of stages with gravity settling between each of said stages with a solution of sodium chloride having a concentration close to the concentration below which the soap may be dissolved.

6. In the manufacture of soap a process for the continuous purification of a glycerinated soap obtained in its most concentrated liquid phase known as neat soap phase comprising washing the soap by a continuous countercurrent circulation in a plurality; of stages with gravity settling between each of said stages with a solution of sodium chloride having a concentration closely above the concentration below which the soap may be dissolved.

7. In the manufacture of soap a process for the continuous purification of a glycerinated soap obtained in the most concentrated liquid phase known as neat soap phase comprising washing the soap by continuous circulation through in part an enlarged zone wherein gravity settling may take place with a solution of sodium chloride having a concentration close to the concentration below which the soap may be dissolved.

8. In the manufacture of soap a process for the continuous purification of a glycerinated soap obtained in the most concentrated liquid phase known as neat soap phase comprising washing the soap by continuous circulation through in part an enlarged zone wherein gravity settling may take place with a solution of sodium chloride having a concentration closely above the concentration below which the soap may be dissolved. FELIX LUCIEN LACHAMPT.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,179,001 Thurman Nov. 7, 1939 2,300,749 Scott Nov. 3, 1942 2,300,751 Scott et al Nov. 3, 1942 2,319,929 Hoffman et a1 May 25, 1943 

